Thermoplastics are used in a variety of end-use applications, including storage containers, medical devices, food packages, cast films, blown films, plastic tubes and pipes, shelving units, and the like. Base thermoplastic resin compositions, however, must exhibit certain physical characteristics to facilitate widespread use. To achieve desirable physical properties, certain compounds and compositions provide nucleation sites for polyolefin crystal growth during molding or fabrication. Generally, compositions containing such nucleating compounds crystallize at a much faster rate and crystallize at high temperature than non-nucleated polyolefins, which is desirable. Such crystallization at faster rate results in reduced fabrication cycle times and a variety of improvements in physical properties such as stiffness or warpage control. Furthermore, the clarity or haze characteristics of such fabricated articles is an important consideration. Articles or films with reduced amounts of haze are generally quite desirable.
Metal salts are useful as nucleating additives for thermoplastics. U.S. Pat. No. 6,599,971 discloses metal salts of HHPA for use in thermoplastics. Other published patents that are commonly owned by the owner of the current application and which relate to metal salt compounds and their use as nucleating agents in polymers include U.S. Pat. Nos. 6,562,890; 6,465,551; 6,642,290; 6,703,434; 6,794,433 and 6,887,963. Other commonly owned patents of interest include U.S. Pat. Nos. 6,936,650 and 6,946,507.
Milliken & Company of Spartanburg, S.C., USA (“Milliken”) markets and sells a nucleating agent composition within its HYPERFORM® nucleating agent additive product line under the designation “HPN-20E™”. The additive product HPN-20™ contains Ca HHPA (as shown below) combined with an acid scavenger compound, zinc stearate. This product is designed for addition to polymers, and for dispersion of the additive into polymer. This solid powdered additive material is made and sold in the United States for use by polyolefin producers and polymer compounders as a direct additive in polyolefin article manufacturing operations.
“Ca HHPA” as referred to herein shall refer to the following compound:

Milliken also markets and sells other compounds as nucleating agents. For example, HYPERFORM® HPN-68L is a powdered solid nucleating agent manufactured by Milliken & Company in which the nucleating agent comprises a dicarboxylate Na-based compound known as HPN-68:
